Electric starter for internal-combustion engines.



B. BROOKS & W. HOLT. ELECTRIC STARTER FOR INTERNAL comsusnow ENGINES.

APPLICATION FILED OCT. 26. 19l4. 1451;139, Patented Aug. 24, 1915.

3 SHEETSSHEET I.

n'msses mvwmmgoazfiec largo/1 5 B. BROOKS & W. HOLT.

ELECTRIC STARTER FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED OCT. 26, I9I4. 1 1 5 1 ,439. Patented Aug. 24, 1915.

3 SHEETSSHEET 2.

I INVENTO RSBOzoZf6ecBrools B. BROOKS (I: W. HOLT. ELECTRIC STARTER FOR'INTERNAL comsusnom ENGINES.

' APPLICATION FILED OCT. 25, I914. 1,151 139, PatentedAug'. 24, 1915.

3 SHEETSSHEET 3.

w (Jam 0 f '7 Ji 2 a rmy BOIILTIBEE BROOKS AND WILLIAM HOLT, OF BIRMINGHAM, ENGLAND.

ELECTRIC STARTER FOR INTERNAL-COMBUSTION ENGINES.

specification of Letters Patent.

Patented Aug. 24., 1915.

Application filed October 26, 1914. Serial No. 868,704..

To all whom it may concern:

Be it knownthat we, BOULTBEE BROOKS and WILLIAM HoL'r, subjects of the King of Great Britain, residing at riterion Works, Great Charles street, Birmingham, England, and 213 Slade Road, Erdington, Birmingham, England, respectively, have invented certain new and useful Improvements in Electric Starters for Internal-Combustion nected with the driving shaft of said motor through the medium of a screw device comprising a projecting part or helical thread on one member engaging with a helical cooperating part provided in connection with the other member, so that when. one of the v said members of the screw device is directly driven by the motor the gear-wheel, owing to its inertia, lags behind the driving shaft and is thereby" traversed axially and taken into gear with a suitable driven member connected with the engine shaft, while as soon as the engine runs under its own power the driven member over-runs thegear-wheel and causes the latter to be traversed axially in the opposite direction and thus to be automatically thrown out of gear.

provide an improved and more efficient starter of the above type.

The present invention consists essentiallyinforming the motor-driven shaft with a hollow or tubular end, around the interior ofv which is formed a helical slot, groove, or screw-thread, which is adapted to be engaged by a stud or pin upon, a spindle or boss carried by the movable gearwheel, or

with a screw-thread formed around the said spindle or boss. And in order to maintain the pinion in its out-of-gear position and also assist the effect of-the inertia of the said pinion, a friction disk -may be provided which engages with the periphery of the driven part when the pinion is taken into gear, but which is moved out of engagement therewith when said pinion is taken out of gear.

The object of the present invention is to Figure 1 of the accompanying drawings represents a section through one end of an electric starting motor having a shiftable gear-wheel or pinion constructed and arranged in accordance with this invention. This view shows the saidpinion in gear with the engine fly-wheel. Fig. 2 is a sectional elevationshowing the pinion in its out-of-gear position. Fig. 3 shows a m0dification in which a friction disk is provided in conjunction with the pinion for the purpose of maintaining the pinion in its out-ofgear position and assisting the inertia. This view shows, by full lines, the pinion in gear, and by dotted lines the position of said pinion when out of gear. Fig. 4 represents another modification. Fig. 5 shows a modified form of friction device which serves to convey the drive from the engine to the dynam0-electric machine when] the latter is driven as a generator, and to reduce the gear ratio of the said drive. Figs. 6 to 8 illustrate further modifications.

Referring to Figs. 1 and 2, l is a serieswound electric motor whose shaft 2 is extended and formed with a hollow sleeve-like or tubular end 3 in which is formed a helical slot 4. This slot is adapted to be engaged by a stud or key 5 upon an elongated boss or stem 6 carried by a toothed gearwheel 7, the said gear-wheel being adapted to be brought intoengagement with a ring of teeth 8 provided around the periphery of the engine fiy-wheel 9. When the engine is not running the gear-wheel 7 is out of engagement with the teeth upon the flywheel, as in Fig. 2 but when the current is switched on to the electric motor, the latter, bein under no load, gains speed very rapi l the toothed gear Wheel 7, however, by reason of its inertia, tends to lag behind the motor shaft. Owing to the stud 5 engaging-within the helical slot 4, a longitudinal movement is imparted to the said gearwheel, and it is drawn inward into mesh with the-teeth upon the fly wheel, as in Fig.

locked together and the drive is transmitted directly to the engine until the latter runs under its own power. As soon as this hapy pens the gear-wheel 7 becomes the driven member and owing to the engine over-running the electric motor it receives a torque in the opposite direction, so that itis caused to travel axially awayfrom the teeth upon the fly-wheel, so that the teeth are disen-' gaged and .the electric motor disconnected from the engine (Fig. 2).

In order to prevent the stud 5 upon the spindle of the gear-wheel from being completely disengaged from the helical slot, there is fitted over the end of the shaft 3 a cap or cover having an annular inwardly extending flange 11, against which the stud 5 abuts when the gear-wheel reaches the end of its outward travel.

' To keep the pinion normally in its out of-gear position, so that the stud 5 bears against the stop, a coiled spring 12 is fitted within a suitable housing in the end of the gear-wheel boss 6 so as to project therefrom and engage with the inner end of the tubuend a of the shaft being formed with a helical slot, as above described, it may be formed with an internal helical groove, or

. screw thread 4, while inanother form instead of a stud or projection being provided upon the gear wheel spindle 6, the latter may be formed (as shown in Fig. 4) with an external screw-thread 5 engaging a heli'-. cal groove inside the tubular part 3. Fig. 3 also shows the use of a friction disk 16 fixed upon the shaft 6 adjacent to the pinion 7 and of slightly larger diameter than the latter, so that when the pinion is in gear the disk engages with the periphery of the flywheel 9, as shown by full lines, but when said pinion is out of gear (shown by dotted lines) then the disk takes a position opposite to a reduced portion 11'of the fiy-wheel, out of engagement with the latter. In this out-of-gear condition the distance of the friction disk from the edge of the larger portion of the flywheel is less than-the distance, between the pinion and the gear ring 8, so that when starting, the friction disk is engaged with the fly-wheel in advance of the pinion '7. The latter, being mounted upon the motor shaft 6, is moved axially when the electric motor is started (due to the inertia of the pinion and friction disk and the rapid acceleration of the motor) and the friction disk 16, coming into engagement with the larger diameter of the fly-wheel, offers a drag or resistance which insures the gear pinion 7 being completely shifted over into engagement with the gear ring 8, so that the drive is conveyed to the engine. When the latter runs under its own power and the fly-wheel overruns gear, and tornaintain it in this condition, as should (by vlbration or otherwise) the pinion be moved toward the gear-ring, the friction disk will engage with the fly-wheel before the pinion can enter into gear, and thus said pinion will be again taken back to its extreme out-of-gear position.

In the modifications represented in Fig. 5 as used' in connection with an electric starting motor adapted to be driven by the engine as a generator, the shaft or boss of the gear pinion 7 carries a friction wheel 16 of considerably larger diameter than the pinion, and when the latter has been thrown out ofgear, as previously described, on the engine commencing to run under its own power, the said friction wheel is moved into gear with another friction wheel19 carried by the fiy-wheel 9 (as shown by dotted lines) so that the drive from the engine is transmitted through the friction wheels 19, 16, to the motor, which is thus driven as a dynamo. The gear ratio is by this means very considerably reduced when the dynamoelectric. runs as a dynamo. The friction wheels may be slightly conical, as shown. The .wheel 16 besides serving to convey the drive from the engine, also acts as a friction drag device for maintaining the toothed pinion in its out-of-gear position and for throwing it into gear when necessary.

If desired, in any of the herein described arrangements a friction drive may be employed for conveying the power from the electric motor to the engine at starting, instead of toothed wheels, as shown in Fig. 6, where 8 is a friction wheel on the flywheel 9, and 7 is a friction pinion on the shaft 6, adapted to be taken into engagement with the wheel 8. Also, instead of a stud on the extension 6 of the gear-wheel engaging the helical slot, a freely rotatable ball 5 (see Fig. 7) may be carried by said extension 6 so as to engage with the helical groove 4.

If desired the pinion 7 may be separately attached to the extension 6 instead of being solid therewith, while the spring 12 may be omitted if convenient. Also, as in Fig. 8, the helical slot or groove 4 may be cut in a separate piece or liner 20 which is inserted in or attached to the hollow shaft 3 of the motor.

-'Having fully described our said invention, what we desire to claim and secure by 7 axial extension, and a shaft driven by the motor having a hollow end engaged by the axial extension of the gear wheel, and hav axial extension of the gear wheel and having a helical guide cooperating with the said projection to cause the gear wheel to be traversed axially whg'n the motoris started and when the engine runs under. its own power, a coiled. spring within the hollow end of the motor shaft for maintaining the gear wheel in its out-of-gear position, and a stop said gear wheel.

3. A starter for internal combustion engines comprising a starting motor, a driven member connected with the engine shaft, a' shiftable gear wheel adapted to engage with said driven member, an axial extension carried by'sai dgearwheel, a projection upon for limiting the outward movement of said axial extension, a shaft driven by the f motor having a hollow end engaged by the axial extension of the gear wheel and having.

a helical guide cooperating with the .said

projection,and a cap fitted upon the hollow end of the shaft and having an internal flange forming a stop for engagement by the pro ection on the axial extension of the gear wheel.

4. A starter for internal combustion engines comprising a starting motor, a driven member connected with the engine shaft,a shiftabl'e gear Wheel adapted-toengage wlth said driven member, an axial extension carried by said gear wheel, .a projection-upon said axial extension, a shaft drivenby the motor having a hollow end engaged by the axial extension of the gear wheel and having a helical guide cooperating with the sai sion of the gear-wheel, an opposed abutment 2 within the hollow end of the motor shaft, and a coiled bufi'er spring interposed between the said shoulders.

projection, a shoulder upon the axial exten- In testimony: whereof we have hereunto set our hands in presence of two subscribing witnesses.

- BOULTBEE BROOKS. 7 WILLIAM HOLT. Witnesses: HENRY NORTON SKERRETT, y

' WILLIAM STAIBES SKERRE'I'L. 

